1. Field of the Invention
The present invention relates to an infrared sensor and, more particularly, to a remote infrared sensor suitable for use on television receivers and tape recorders including video tape recorders.
2. Description of the Prior Art
Recent television receivers and VTRs, in general, are provided with a remote infrared sensor which receives and processes control signals provided by a remote controller. The conventional remote infrared sensor employs a photodetector including a pin diode. The conventional remote infrared sensor comprises a sensing unit having a photodetector employing a pin photodiode, a signal processing circuit comprising a signal amplifier and a frequency band controller, and a metallic box accommodating the sensing unit and the signal processing circuit. This conventional remote infrared sensor comprises about ten component parts and requires assembling processes for assembling those component parts. Therefore, it is difficult to fabricate the remote infrared sensor at a high productivity and to reduce the cost.
FIG. 4 shows a previously proposed remote infrared sensor B intended to improve the productivity of the manufacturing process and to reduce the cost. The remote infrared sensor B is a monolithic remote infrared sensor comprising: a p-type silicon substrate 22; a photodetector 21 comprising a plurality of pn junctions formed, for example, by forming a p-type diffused region on an n-type epitaxial layer on the p-type silicon substrate 22; a signal processing circuit 23 formed on the p-type silicon substrate 22; and bonding pads 24. This remote infrared sensor B can be fabricated at a high productivity and at a relatively low cost.
Since both the photodetector 21 and the signal processing circuit 23 of this previously proposed remote infrared sensor B are formed on the same substrate 22, infrared radiation to be received by the photodetector 21 falls also on the signal processing circuit 23, causing the signal processing circuit 23 to generate noise due to a photocurrent induced therein by the infrared radiation.